研究背景
胃癌是全世界發(fā)病率第五、腫瘤死亡率高居第三的常見惡性腫瘤[1]。其中，大約有40%胃癌發(fā)生于中國(guó)，多數(shù)人被診斷為胃癌時(shí)已是進(jìn)展期，更容易轉(zhuǎn)移或者復(fù)發(fā)[2]。無(wú)論是早期胃癌還是晚期胃癌，腹膜轉(zhuǎn)移都是最常見的轉(zhuǎn)移或者復(fù)發(fā)方式[3-5]。由于目前沒有有效的治療手段，胃癌一旦發(fā)生腹膜轉(zhuǎn)移，患者的中位生存時(shí)間不足6個(gè)月，因此，闡明胃癌腹膜轉(zhuǎn)移的分子機(jī)制改善其預(yù)后是亟待解決的問題。
二代測(cè)序作為精準(zhǔn)醫(yī)療的關(guān)鍵技術(shù)，可發(fā)現(xiàn)腫瘤相關(guān)的靶基因，為個(gè)體化治療提供靶標(biāo)，使得腫瘤的研究發(fā)生重要變革[6, 7]。全外顯子測(cè)序(WES)針對(duì)人類基因組的1%進(jìn)行測(cè)序，可獲得較好的測(cè)序深度，有利于發(fā)現(xiàn)轉(zhuǎn)移灶基因改變的信息[8-10]。
胃腺癌是胃癌最常見的組織類型，一旦發(fā)生腹膜轉(zhuǎn)移，手術(shù)將不再作為最優(yōu)的治療手段，因此，同時(shí)獲取胃癌原發(fā)灶和配對(duì)的轉(zhuǎn)移灶變得極為困難。然而，近年來(lái)，減瘤手術(shù)被認(rèn)為是一種可以是腹膜轉(zhuǎn)移生存患者獲益的治療方式[9]。本研究選取一例胃腺癌患者的原發(fā)灶，腹膜轉(zhuǎn)移灶以及各自配對(duì)的正常組織，進(jìn)行全外顯子測(cè)序，旨在發(fā)現(xiàn)胃癌腹膜轉(zhuǎn)移的突變基因。


研究思路

研究結(jié)果
我們選用llumminaHiSeq2500測(cè)序儀，雙端測(cè)序，讀長(zhǎng)100nt，用WES測(cè)序發(fā)現(xiàn)了胃癌原發(fā)灶的48個(gè)體細(xì)胞單核苷酸突變（SNP），腹膜轉(zhuǎn)移灶49個(gè)SNP,G>A和C>T是突變頻率最高的類型（圖1）。通過(guò)Sanger測(cè)序分別驗(yàn)證了原發(fā)灶和轉(zhuǎn)移灶中的SNP，原發(fā)灶和腹膜轉(zhuǎn)移灶中的非同義體細(xì)胞突變分別有27和35個(gè)得到驗(yàn)證（圖2，3）。并同體細(xì)胞突變數(shù)據(jù)庫(kù)COSMIC中的胃癌數(shù)據(jù)經(jīng)行了比較，發(fā)現(xiàn)了突變頻率高于5%的基因（BAI1,ARID2,THSD1,KIAA2022），以及尚未在該數(shù)據(jù)庫(kù)中出現(xiàn)的突變基因，還有部分SNP僅僅發(fā)生腹膜轉(zhuǎn)移灶（ERBB4, ZNF721, NT5E, PDE10A, CA1, NUMB, NBN, ZFYVE16, NCAMI），他們可能是胃癌發(fā)生腹膜轉(zhuǎn)移的驅(qū)動(dòng)基因，其機(jī)制有待進(jìn)一步研究。因此，我們發(fā)現(xiàn)胃癌腹膜轉(zhuǎn)移灶中的大多數(shù)非同義體細(xì)胞突都與原發(fā)灶相同，有少數(shù)是不同于原發(fā)灶突變。該研究中全外顯子測(cè)序服務(wù)及數(shù)據(jù)分析服務(wù)由上海伯豪生物技術(shù)有限公司提供。

參考文獻(xiàn)
1. Torre LA, Bray F, Siegel RL, Ferlay J, Lortet-Tieulent J and Jemal A. Global cancer statistics, 2012. CA: a cancer journal for clinicians. 2015; 65(2):87-108.
2. Zhang J, Huang JY, Chen YN, Yuan F, Zhang H, Yan FH, Wang MJ, Wang G, Su M, Lu G, Huang Y, Dai H, Ji J, Zhang J, Zhang JN, Jiang YN, et al. Whole genome and transcriptome sequencing of matched primary and peritoneal metastatic gastric carcinoma. Scientific reports. 2015; 5:13750.
3. Huang B, Sun Z, Wang Z, Lu C, Xing C, Zhao B and Xu H. Factors associated with peritoneal metastasis in non-serosa-invasive gastric cancer: a retrospective study of a prospectively-collected database. BMC cancer. 2013; 13:57.
4. Kerkar SP, Kemp CD, Duffy A, Kammula US, Schrump DS, Kwong KF, Quezado M, Goldspiel BR, Venkatesan A, Berger A, Walker M, Toomey MA, Steinberg SM, Giaccone G, Rosenberg SA and Avital I. The GYMSSA trial: a prospective randomized trial comparing gastrectomy, metastasectomy plus systemic therapy versus systemic therapy alone. Trials. 2009; 10:121.
5. Kodera Y, Yamamura Y, Shimizu Y, Torii A, Hirai T, Yasui K, Morimoto T and Kato T. Peritoneal washing cytology: prognostic value of positive findings in patients with gastric carcinoma undergoing a potentially curative resection. Journal of surgical oncology. 1999; 72(2):60-64; discussion 64-65.
6. Lin Y, Wu Z, Guo W and Li J. Gene mutations in gastric cancer: a review of recent next-generation sequencing studies. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine. 2015; 36(10):7385-7394.
7. Chen K, Yang D, Li X, Sun B, Song F, Cao W, Brat DJ, Gao Z, Li H, Liang H, Zhao Y, Zheng H, Li M, Buckner J, Patterson SD, Ye X, et al. Mutational landscape of gastric adenocarcinoma in Chinese: implications for prognosis and therapy. Proceedings of the National Academy of Sciences of the United States of America. 2015; 112(4):1107-1112.
8. Liu X, Wang J and Chen L. Whole-exome sequencing reveals recurrent somatic mutation networks in cancer. Cancer letters. 2013; 340(2):270-276.
9. Hartgrink HH, Putter H, Klein Kranenbarg E, Bonenkamp JJ, van de Velde CJ and Dutch Gastric Cancer G. Value of palliative resection in gastric cancer. The British journal of surgery. 2002; 89(11):1438-1443.
10. Beltran H, Eng K, Mosquera JM, Sigaras A, Romanel A, Rennert H, Kossai M, Pauli C, Faltas B, Fontugne J, Park K, Banfelder J, Prandi D, Madhukar N, Zhang T, Padilla J, et al. Whole-Exome Sequencing of Metastatic Cancer and Biomarkers of Treatment Response. JAMA oncology. 2015; 1(4):466-474.

原文出處
Liu H, Li F, Zhu Y, Li T, Huang H, Lin T, Hu Y, Qi X, Yu J, Li G. Whole-exome sequencing to identify somatic mutations in peritoneal metastatic gastric adenocarcinoma: A preliminary study. Oncotarget.2016.